Linux Kernel v2.4.31-sparc-r2 Configuration
│ CONFIG_WDC_ALI15X3:
│ This allows for UltraDMA support for WDC drives that ignore CRC
│ checking. You are a fool for enabling this option, but there have
│ been requests. DO NOT COMPLAIN IF YOUR DRIVE HAS FS CORRUPTION, IF
│ YOU ENABLE THIS! No one will listen, just laugh for ignoring this
│ SERIOUS WARNING.
│
│ Using this option can allow WDC drives to run at ATA-4/5 transfer
│ rates with only an ATA-2 support structure.
│
│ SAY N!

but this does not seem to be my case because M5229 != 15x3 or ma i mistaken?

M5229 == ALi1543. But that's not the problem. The ALi chipset has known data corruption problems in UDMA mode, depending on its revision. Your revision (c3) should be fine but the driver tends to err on the safe side of things when performing aqutodetection. You need to patch alim15x3.c to work around this issue, sorry.
AFAIK kernels > 2.6.8 don't exhibit the issue anymore, but I didn't try them (gave up on the ALi chipset completely)._________________Military Commissions Act of 2006: http://tinyurl.com/jrcto